document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1079080>Question 1079080</A>: <I><SPAN STYLE=\"word-break: break-all;\"> After the release of radioactive material into the atmosphere from a nuclear power plant in a country in 1987&#8203;, the hay in that country was contaminated by a radioactive isotope&#8203; (half-life 6 &#8203;days). If it is safe to feed the hay to cows when 88&#8203;% of the radioactive isotope is&#8203; gone, how long did the farmers need to wait to use this&#8203; hay? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #693445 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=693445\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> P=Poe^(-kt)<BR>\n" );
document.write( "1/2=e^(-6k)<BR>\n" );
document.write( "ln of both sides<BR>\n" );
document.write( "-0.693=-6k<BR>\n" );
document.write( "k=0.1155<BR>\n" );
document.write( "0.12=e^(-.1155*t)<BR>\n" );
document.write( "ln of both sides<BR>\n" );
document.write( "-2.12=-.1155t<BR>\n" );
document.write( "t=18.35 days.<BR>\n" );
document.write( "Check.<BR>\n" );
document.write( "half gone in 6 days<BR>\n" );
document.write( "three-quarters gone in 12 days<BR>\n" );
document.write( "seven-eights gone i 18 days. (0.125)<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );